To produce semiconductor integrated circuits, a manufacturing process (wafer process) to produce semiconductor product wafers must take place first. The manufacturing process (or wafer process) includes a large number of process steps to process semiconductor substrates (wafers). When the wafer process is completed, the wafer becomes a product wafer having a plurality of semiconductor integrated circuit chips (product chips) formed in respective chip areas on the wafer. The chips are, then, separated into individual dies at scribe lines between the chip areas. The dies are then packaged to become semiconductor integrated circuit products.
In one conventional manufacturing process of a semiconductor product wafer, a series of product masks are employed on an evaluation wafer in a series of mask-enabled processing steps. The evaluation regions of interest on the evaluation wafer are then inspected to help identify failures in any of the mask-enabled processing steps so that corrections or improvements can be made to any of the identified processing steps. However, not all of the problems or failures of the mask-enabled processing steps are observable in the evaluation wafer when using only product masks.